Pre-Choosing Race for a multiplayer map?

How can you pre-choose the race of a player in a multiplayer map, like make all people human and not be able to change it?

Also, how can you make some automatically a computer player? (I need to make 2 players computer so they attack each other forever (they just show the creators names :) ) )

Look under the scenario menu. It's "player properties"

I did this is all my maps, but they still end up being players/usable slots when they're saved, its silly.